Plasma Oxytocin Concentration in Pre- and Postmenopausal Women: Its Relationship with Obesity, Body Composition and Metabolic Variables.

OBJECTIVE: To investigate the relationship between oxytocin, menopause and obesity. METHODS: A cross-sectional analysis on 56 obese (OB; 28 premenopausal) and 53 normal-weight women (NW; 27 premenopausal) was performed by measurement of oxytocin, leptin, adiponectin, gonadotropins, sex steroids, glucose, and lipid homeostasis as well as DXA assessment of fat mass (%FM) and fat-free mass (FFM). RESULTS: Women from NW and OB groups were comparable for age but differed in anthropometric measures. In our cohorts, menopause was not associated with changes in gluco-lipid homeostasis and %FM, while FFM was lower in postmenopausal women from both study groups (p < 0.05). In each group, leptin was unaltered, and adiponectin only marginally changed across menopause, while oxytocin levels were lower in post- than in premenopausal women (NW: p < 0.05; OB: p < 0.005), and lower in OB than NW women, either when assessed as whole groups or if stratified by menopause (p < 0.001). In correlation analysis, inverse associations related oxytocin to menopause, obesity, and adiposity-related measures. BMI (p < 0.0001) and menopause independently predicted oxytocin levels (p < 0.001), but their interaction was null (p = 0.5). CONCLUSIONS: Obesity and menopause are independent negative predictors of plasma oxytocin. Longitudinal studies should clarify the role of oxytocin on weight modifications experienced around and after menopause.

Interferon-inducible genes, TNF-related apoptosis-inducing ligand (TRAIL) and interferon inducible protein 27 (IFI27) are negatively regulated in leiomyomas: implications for a role of the interferon pathway in leiomyoma development.

Uterine leiomyomas are the most common tumors in the human female pelvis and the leading indication for pelvic surgery. Lack of understanding of the molecular pathogenesis of leiomyoma has put severe limitations on the availability of alternative treatments. Using an oligonucleotide micro-array-based hybridisation analysis we observed a group of genes with a broad range of functional activity differentially expressed in smooth muscle cells (SMC) derived from leiomyomas when compared to matched myometrial cells. Among them, two IFNα inducible genes, TRAIL and IFI27, were underexpressed in leiomyoma vs. myometrial cells. Expression levels of TRAIL and IFI27 were also measured in myometrial and leiomyoma cells by real-time quantitative PCR in basal condition and after IFNα stimulation. In both cell types, the transcription of the two genes resulted induced by IFNα but the IFI27 transcription stimulation was weaker in leiomyoma than myometrial cells whereas the TRAIL transcription stimulation resulted stronger in leiomyoma respect myometrial cells. Based on this finding and on previous observations we have hypothesized that a reduced response to IFNα stimulation might be involved in leiomyoma formation and growth.

Investigations of thyroid hormones and antibodies in obesity: leptin levels are associated with thyroid autoimmunity independent of bioanthropometric, hormonal, and weight-related determinants.

OBJECTIVES: Obesity can alter the thyroid hormone status as a result of a dysregulated endocrine loop between the hypothalamo-pituitary unit and adipose tissue. The adipocytokine leptin has been shown to promote autoimmunity; hence, we aimed to clarify whether leptin excess of obesity could increase the susceptibility to develop autoimmune thyroid disease (AITD). STUDY DESIGN: This cross-sectional study was performed in a tertiary care center. METHODS: Free thyroid hormones, TSH, thyroglobulin, and antithyroid antibodies levels were tested in 165 obese and 118 lean subjects. Results were plotted against variables related to body composition, leptin levels, glucose homeostasis, energy expenditure, and pattern of weight accrual. RESULTS: Compared with controls, obese patients had lower free T3 levels and free T4 levels (P<0.01), greater prevalence of hypothyroidism (P<0.05), and higher commonness of antithyroid antibodies (P<0.05). As a marker of AITD, thyroid peroxidase antibodies were more frequent in the obese group (P<0.01). Correlation analysis showed that leptin levels were associated with AITD (P<0.01) independent of bioanthropometric variables. Multiple logistic regression analysis in pooled groups identified female sex and leptin as significant predictors of AITD. CONCLUSIONS: Obesity increases the susceptibility to harbor AITD with an emerging role for leptin as a peripheral determinant, which needs to be confirmed in future investigations.

The relationship between active ghrelin levels and human obesity involves alterations in resting energy expenditure.

Ghrelin is a gastric hormone that exerts a stimulatory effect on appetite and fat accumulation. Ser(3) octanoylation is regarded as a prerequisite for ghrelin biological activity, although des-octanoylated forms may retain biological functions in vitro. Circulating ghrelin levels are usually low in obesity and in states of positive energy balance. Hence, the aim of our study was to analyze plasma active and serum total ghrelin levels in 20 obese (ages, 22-42 yr; body mass index, 41.3 +/- 1.1 kg/m(2)) and 20 lean subjects (ages, 22-43 yr; body mass index, 22.4 +/- 0.6 kg/m(2)) as well as their relationship to measures of glucose homeostasis, body fat, and resting energy expenditure (REE). The measured/predicted REE percentage ratio was calculated to subdivide groups into those with positive (> or = 100% ) and negative (<100%) ratio values. In obese patients, plasma active (180 +/- 18 vs. 411 +/- 57 pg/ml; P < 0.001) and serum total ghrelin levels (3650 +/- 408 vs. 5263 +/- 643 pg/ml; P < 0.05) were significantly lower when compared with lean subjects. Hence, ghrelin activity, defined as the proportion of active over total ghrelin levels, was similarly reduced in the obese state (6.1 +/- 0.9% vs. 8.4 +/- 1%; P < 0.05). There was a significant correlation between active and total ghrelin (r = 0.62; P < 0.001), and between total ghrelin and insulin (r = -0.53; P < 0.001) or insulin resistance using the homeostatis model of assessment-insulin resistance (r = -0.49; P < 0.001) approach. Significantly higher active ghrelin levels (214 +/- 22 vs. 159 +/- 30 pg/ml; P < 0.05) and ghrelin activity (8 +/- 1.7% vs. 4.9 +/- 0.9%; P < 0.05) were observed in patients with positive compared with negative measured/predicted REE ratio values. Our study shows that obesity is associated with an impairment of the entire ghrelin system. The observation that ghrelin is further decreased in cases of abnormal energy profit adds new evidence to the relationship between ghrelin activity and energy balance in obesity.